The present invention relates to a beater bar capable of being acted upon on one side for impactor rotors.
More particularly, it relates to a beater bar which is capable of being inserted form-fittedly into circumferential slots of the rotors and which has rearwards, opposite to the direction of rotation of the rotors, and facing these, a bend of its elongate cross section, by means of which it engages into a longitudinally running undercut of the circumferential slots and is held counter to the centrifugal force of the rotating rotors, with bearing surfaces, by means of which the beater bar is held against a bearing surface of the rotors, and with a supporting surface, via which the beater bar is in engagement with the undercut in the circumferential slots by means of a supporting or bearing piece.
A beater bar of this type is known from U.S. Pat. No. 3,151,816. It has, on its rear side, a right-angled bend which engages under an undercut of the bearing surface of the circumferential slots in the rotor. The narrow side, facing the rotor, of the beater bar is bevelled, and against this bevel presses a wedge which is supported adjustably by means of pressure screws against the front surface of the circumferential slots which faces the beater bar. Exchangeable press plates are provided between the pressure screws and the front surface of the circumferential slots, and the wedge is additionally guided by lateral abutments. Fixing the beater bar in this way is complicated and costly, particularly since the parts necessary for this purpose are particularly exposed to wear at this point. The fastening of the beater bar is also unreliable, in that, if there is inadequate maintenance or inspection, the wedges may come loose in the rotating rotor, together with their pressure screws and the other aids, thus entailing the risk that the beater bar will fly out of its mounting and cause serious damage to the impactor. A sharp-edged undercut of the circumferential slots and the corresponding sharp-edged bend of the beater bar require accurate machining of the corresponding edges and surfaces, but are also undesirable because of the notch effects which may possibly occur here.
Beater bars capable of being acted upon on one side are known in many forms, even those which have bends or similar means for fastening. As a rule, they are fastened to the rotor body by means of wedges or wedge-shaped aids and additionally also by means of screw connections (U.S. Pat. No. 3,874,603, German patent specification 16 07 552, Australian patent specification 253,653), or they are pushed into circumferential recesses of disc rotors (DE-27 59 250 A1). Whilst in the case of the first-mentioned beater bars the fastening is complicated and they have the disadvantages described in more detail above, in the case of the last-mentioned beater bars there is additionally also the problem that the slots between the beater bars and the rotor contours surrounding these become clogged with fine material and obstruct the removal which is necessary after the wear of the beater bars.
Beater bars capable of being acted upon on one side are per se uneconomic because of their low wear potential. For a long time, therefore, beater bars have been used which are rotatable about their longitudinal axis and/or transverse axis and are inserted loosely into circumferential slots of the rotors (German utility pattern 1 831 058, DE 37 42 395 C1). On account of the clearances in the form of gaps which are necessary for this purpose, even with these beater bars the gaps become clogged with fine material, and, besides, the rotation or turning of the beater bars is time-consuming and therefore costly. Also, these known beater bars have only a low degree of utilization because of their relatively large clamping height. However, in view of high wages, the maintenance costs are increasingly decisive as regards profitability.